scsi: simplify scsi_free_sgtable()

Just pass in the command, no point in passing in the scatterlist
and scatterlist pool index seperately.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 960f949..7e1dcc5 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -741,13 +741,14 @@
 
 EXPORT_SYMBOL(scsi_alloc_sgtable);
 
-void scsi_free_sgtable(struct scatterlist *sgl, int index)
+void scsi_free_sgtable(struct scsi_cmnd *cmd)
 {
+	struct scatterlist *sgl = cmd->request_buffer;
 	struct scsi_host_sg_pool *sgp;
 
-	BUG_ON(index >= SG_MEMPOOL_NR);
+	BUG_ON(cmd->sglist_len >= SG_MEMPOOL_NR);
 
-	sgp = scsi_sg_pools + index;
+	sgp = scsi_sg_pools + cmd->sglist_len;
 	mempool_free(sgl, sgp->pool);
 }
 
@@ -773,7 +774,7 @@
 static void scsi_release_buffers(struct scsi_cmnd *cmd)
 {
 	if (cmd->use_sg)
-		scsi_free_sgtable(cmd->request_buffer, cmd->sglist_len);
+		scsi_free_sgtable(cmd);
 
 	/*
 	 * Zero these out.  They now point to freed memory, and it is